Intravascular catheter systems, such as peripheral intravenous catheters or central venous catheters, for example, are essential in modern medical practice. Catheter systems are commonly used for fluid infusion or withdrawal, or for monitoring various physiological parameters, such as blood pressure, pH and blood gas tensions. Catheter systems may be also used for introducing and locating probes, such as blood gas- or blood pressure probes.
Conventional method of placing the catheter into a blood vessel using over-the-needle technique comprises skin puncture with an introducer needle, moving the needle in surrounding tissues forward towards target blood vessel, puncturing the wall of a target blood vessel and pushing a catheter inside target blood vessel while removing a needle. In case of over-the-wire technique a guidewire is used prior to placement or insertion of the catheter inside of the blood vessel. An indication of a successful blood vessel puncture is a blood flow into a flashback chamber that is commonly visually observed. However, one of the major problems during venipuncture or arterial line placement is difficulty in determination of the exact position of a needle tip inside the skin relatively to a blood vessel. In most conventional systems venipuncture is performed based on the results of both visual observation and palpation of skin area to be punctured, and often a blood vessel is not located correctly on a first try. Also blood vessels, otherwise visible through the light skin may not be as well detectable through the dark skin. Another problem is that, an observation of blood flow to a flashback chamber is not always a reliable indicator of blood vessel's wall penetration. Some amount of blood may also appear in the flashback chamber whether the needle penetrates blood vessel throughout, thus ending up not in the lumen of the blood vessel, but in surrounding tissues. In case a clinician is not always able to recognize the fact of throughout penetration, catheter placement into an incorrectly punctured blood vessel may cause a permanent damage of a blood vessel. Hereto relates another problem of clinician might be unaware of a moment when to stop pushing the needle forward inside the blood vessel, which may also be the reason for damaging blood vessel from inside. In fact, correct positioning of a catheter system on any patient with small, deep, faulty or damaged veins is conjugated with aforesaid problems. All above mentioned problems become especially noticeable in case of emergency, ambulance and/or in children's hospitals.
Blood vessel entry indicator means for catheter systems, other than observation of blood flow into a flashback chamber, have been developed.
A device, producing sound signal upon entering blood vessel, is known from U.S. Pat. No. 5,954,701.
Blood vessel entry visual indicator, operating via inflating a mechanical part inside said device in response to blood pressure, is disclosed in U.S. Pat. No. 5,314,410.
US 2007/073160 discloses a light-guided catheter assembly with inside-out transcutaneous illumination and visualization of its placement through the skin and its application method.
The method thereof is based on a photochemical reaction, wherein an optical signal radiates back from fluorescenting molecules present in patient's blood stream and is further guided to a detector.
An intravenous puncture assembly with blood vessel location means based on visual detection of color change of crystalline material inside the needle hub is provided in U.S. Pat. No. 4,971,068.
U.S. Pat. No. 4,311,138 discloses an illuminated hypodermic catheter needle assembly adapted to emit light from its distal end to facilitate venipuncture under subdued lighting conditions. However, said device enables the needle to be seen through skin, while no indication of the detection of a successful blood vessel penetration is given. An indication of the correct position of the needle is provided by reflux of blood back through the needle, i.e. a clinician ends up with visual observation of blood flowing to a flashback chamber.
Blood visualization systems based on optical radiation absorption by hemoglobin are promising, but rather poorly developed. Devices known from previous patent publications are either rather complicated in use or have never been put into practice. However, the phenomena of absorption of optical radiation of certain wavelength by hemoglobin may be successfully implemented in medical devices intended for puncturing blood vessels. What is needed is to provide a fast, easy, accurate and consistent device for blood vessel puncture, capable of providing reliable indication of blood vessel entry other than visual observation of blood flow into a flashback chamber. It is further desirable that said device would not require any additional equipment, like e.g. detectors or goggles, in order to be easily applicable in emergency situations.